The objective of the research program is to investigate the nervous system control of jaw movement. Studies will be undertaken concerning the mechanisms by which the influence of cortical and subcortical centers interact with feedback from intra-oral receptors to integrate the activity of the interneurons and motoneurons which control jaw movements. Neurophysiologic and neuroanatomic investigations will be performed on experimental animals involving the effect of stimulation of intra-oral receptors on reflexes of the trigeminal system. Emphasis will be placed on the study of the activity of neurons in the trigeminal mesencephalic, main sensory, and motor nuclei during rhythmic jaw movements evoked by electrical stimulation of cortical and subcortical sites. Electromyography of the muscles of mastication in human subjects will be utilized to study oral reflexes both in normal subjects and in patients with neuromuscular disorders of the masticatory apparatus. Simple methods for testing oral reflexes in human subjects will be developed which may be utilized for the diagnosis and treatment of disorders of the masticatory system.